A wafer level package (WLP) is known as an example of a semiconductor package (semiconductor device) that includes a semiconductor element (electronic component), such as a bare chip. A WLP is also called a wafer-level chip size package (WL-CSP) or a wafer chip size package (W-CSP). A WLP enables terminals located at an end of a bare chip to be rearranged in a chip area (i.e., fan-in). Furthermore, a WLP that enables terminals to be rearranged outside a chip area (i.e., fan-out) is also being developed, because it becomes difficult to rearrange the terminals within the chip area as the number of the terminals of a bare chip increases.
In a known method of manufacturing such semiconductor packages, semiconductor elements are attached to an adhesive sheet or adhesive layer, which is composed of an adhesive material, provided on a support member and are sealed with resin to form a pseudo wafer; the pseudo wafer is separated from the adhesive layer; a wiring layer is formed on a surface of the pseudo wafer separated from the adhesive layer; and the pseudo wafer is diced.
Thus, individual semiconductor packages are obtained. In this manufacturing method, the pseudo wafer is separated from the adhesive layer by reducing the adhesion of the adhesive layer through, for example, ultraviolet irradiation, chemical treatment, or heating treatment.
In another known method, the adhesive layer is composed of an adhesive material that has release properties and solvent solubility effective against the resin used to seal the semiconductor elements.
Examples of related art are as follows: U.S. Pat. No. 7,202,107B2 specification, Japanese Patent No. 4403631, and Japanese Laid-open Patent Publication No. 2002-299500.
In a method of separating, from an adhesive layer, a pseudo wafer (substrate) formed on the adhesive layer, the adhesive layer may be subjected to ultraviolet irradiation, chemical treatment, or heating treatment to reduce the adhesion of the adhesive layer.
Once the adhesion of an adhesive layer is reduced, however, it is difficult to reuse the adhesive layer, and a new adhesive layer is used every time a pseudo wafer is formed. Accordingly, it is difficult to reduce man-hours and cost for manufacturing a semiconductor device (semiconductor package). In addition, using the semiconductor device manufactured as described above may increase costs of electronic devices.